Method of preparing cellulose pulp



Patented Nov. 4, 1930 UNITED STATES PATENT OFFICE HARRY L. HORN, OF NEW YORK, N. Y., ASSIGNOR TO BAGASSE DEVELOPMENT INC., A CORPORATION OF NEW YORK METHOD OF PREPARING CELLULOSE PULP No Drawing.

This invention relates to new and useful improvements in'a method of preparing cellulose pulp from cellulose bearing material such as bagasse, straws, grasses, wood, cornstalk and the like.

The invention relates to similar subject matter as disclosed in my copending application, Serial Number 410,702, filed simultaneously with this application.

The invention proposes simultaneous cooking, beating and electrically and chemically treating bagasse, straws, grasses, wood, cornstalk and the like for forming a pulp capable of being used in well known manner for manufacturing paper, rayon, etc., and which besides distinguishing in the reduction of the cost of the pulp, differs in the production of a higher grade of pulp. It may be obvious that if various steps of a method could be performed simultaneous, that time will be saved, but the producing of a superior product or the possibility of simultaneously performing all of the steps without interference of the steps with each other could not preyiously be recognized, except by actual trymg.

Specific application of the instant invention will be given as it relates to bagasse which is typical of the various cellulose materials previously mentioned. It may be well to call attention that sugar cane is usually cut by a hand cutter a few inches above the ground, because the vegetation of the cane occurs in a junglelike field. After the sugar cane is cut, it is heaped and loaded in a cart and delivered to a factory. The upper part of the cane which forms the leaves and branches is removed and the cane proper is dumped into a crushing machine. The crushing machine has crushing rollers which squeeze out the juice which is used for preparing sugar. The remainder is the bagasse. Millions of tons of this bag-asse must be carried away from the sugar mills and destroyed by burning or otherwise.

Numerous attempts have been made to com mercially use the bagasse in the production of pulp for the manufacture of paper, rayon and the like, but have failed in that the cost was prohibitive or the product unsatisfactory.

Application filed December 2, 1929. Serial No. 411,219.

The present invention .utilizes this bagasse so that it is possible to refine it and make pulp of good quality cheaply and on a commercial basis.

The pulp produced may be used for making paper, rayon or the like, by methods which are well known. For example, one method is cited which consists in feeding the pulp as obtained from the crusher to a conveyor, drying out the moisture from the pulp by a suitable suction device beneath the conveyer and spreading the pulp into paper sheets after the removal of the moisture. It is necessary to refine the pulp before feeding it to the conveyer by various treatments and coloring to conform with particular requirements. The paper may be manufactured to be of different grades depending upon the quality or thickness of the fibres in the pulp which is of cottonlike texture.

The above method of making paper is conventional, but the particular transforming of the bagasse into pulp as follows, is new. The shredded bagasse as obtained from the crusher must first be washed for removing various impurities such as the remains of the juice dirt, sand and other foreign matter, and then must be fed into a container which is generally known as a digest or by means of a conveyer or thru a manhole. Water is supplied into the conveyer with the shredded bagasse preferably a sufficient amount to cover all of the latter element. A plurality of rods are loosely located in the bottom part of the digestor so that upon rotation these rods may move around and accomplish proper beating of the shredded bagasse.

These rods may be round or of any other suitable shape and may be formed with depressions, slots, grooves or the like.

Sodium chloride is added to the water in the digester and one terminal of an electric source is connected at one end of the digestor and the other terminal to the other end. The current is then passed thru the liquid in the. digestor and electrolytical and chemical action takes place forming sodium hydroxide and chlorine, and siml'lltaneously the digestor is rotated by mechanical means for about two hours. This treatment constitutes a powerful softening agent for the shredded bagasse. It is advisable that 10 pounds of sodium chloride be added to 100 pounds of shredded bagasse in 100 gallons of Water;

After two hours of rotation, the digestor is stopped and lime and soda ash is added. Then the digestor is again rotated and simultaneously steam is supplied within it at a pressure of from thirty to fifty pounds. The digestor is now allowed to rotate for a period of from one to two hours. During this period, the steam cooks the contents of the digestor and adds to the softening of the bagasse. Preferably the digestor should rotate at eighteen revolutions per minute. When the machine is stopped, the material is dumped into a container and the juice or water drains off. The resultant matter is the pulp which is to be used in the preparation of paper, rayon and the like by any conventional method. The

juice or water may be used for the recovery of by-products such as fertilizers, etc.

The invention method eliminates the necessity of many operations. It eliminates the beating of the pulp either partially or completely and the result is far more eflicient than if pulp would be produced by separate steps since cooking, beating, electrical and chemical processes all take place simultaneously and in united action more efiiciently and thoroughly accomplish their results than if they were acting singularly.

While I have described my invention with some degree of particularity, I realize that in practice various alterations therein may be made. I therefore reserve the right and privilege of changing the form of the details or otherwise altering the arrangement of the correlated sparts without departing from the spirit or the scope of the appended claims.

Having thus described my invention, what I claim as new, and desire to secure by United States Letters Patent is 1. A method for-preparing cellulose pulp from cellulose bearing material such as bagasse, straws, grasses, wood, cornstalk and the like, consisting in simultaneously cooking, beating and electrically and chemically treating the cellulose bearing material.

2. A method for preparing cellulose pulp from cellulose bearing material such as bagasse, straws, grasses, wood, cornstalk, and the like, consisting in simultaneously cooking, beating and'electrically and chemically treating the cellulose bearing material, said cooking being accomplished by the introduction of steam into a digestor rotating and carrying the cellulose bearing material in water.

3. A method for preparing cellulose pulp from cellulose bearing material such as bagasse, straws grasses, Wood, cornstalk, and the like, consisting in simultaneously cooking, beating and electrically and chemically treating the cellulose bearing material, said cooking being accomplished by the introduction of steam into a digestor rotating and carrying the cellulose bearing material in water, said beating being accomplished by loose rods within the digestor.

4. A method for preparing cellulose pulp from cellulose bearing material such as bagasse, straws, grasses, wood, cornstalk and the like, consisting in simultaneously cooking, beating and electrically and chemically treating the cellulose bearing material, said cooking being accomplished by the introduction of steam into a digestor rotating and carrying the cellulose bearing material in water, said electrical and chemical treatment con. sists in passing a current thru said water to which sodium chloride has been previously added.

5. A method for preparing cellulose pulp from cellulose bearing material such as bagasse, straws, grasses, wood, cornstalk and the like, consisting in simultaneously cooking, beating and electrically and chemically treating the cellulose bearing material, said cooking being accomplished by the introduction of steam into a digestor rotating and carrying the cellulose bearing material in water, said electrical and chemical treatment consists in passing a current thru said water to which sodium chloride has been previously added, and at a later soda ash.

6. A method of preparing cellulose pulp from cellulose bearing material, comprising simultaneous cooking, beating and electrically and chemically treating the material, said chemical treatment including the use of a softening agent.

In testimony whereof I have aflixed my sig nature.

HARRY L. HORN.

period adding lime and- 

